A DC battery pack can be used in an electromechanical system to energize a polyphase electric machine. In such a system, a power inverter module (PIM) converts the DC output of the battery pack, typically via high-speed semiconductor switching, into AC power suitable for driving the electric machine. The same inverter module may be used to convert AC power into DC power for recharging the battery pack. For this reason, PIMs are used as an integral component of hybrid electric, extended-range electric, and battery electric vehicle powertrains.